package net.lzzy.practices.services;

import net.lzzy.practices.constants.Messages;
import net.lzzy.practices.entities.Chapter;
import net.lzzy.practices.entities.Course;
import net.lzzy.practices.entities.User;
import net.lzzy.practices.repositories.ChapterRepository;
import net.lzzy.practices.repositories.CourseRepository;
import net.lzzy.practices.utils.AuthUtils;
import org.springframework.stereotype.Service;

import java.util.Date;
import java.util.List;
import java.util.UUID;

/**
 * @author  Jaymo on 2022/5/30
 */
@Service
public class ChapterServiceImpl  implements  ChapterService{
    private  final ChapterRepository repository;
    private  final CourseRepository cRepository;

    public  ChapterServiceImpl(ChapterRepository repository, CourseRepository cRepository){
        this.repository = repository;
        this.cRepository = cRepository;
    }

    @Override
    public  List<Chapter> getTeachersChapters(UUID courseId, String token){
     if (checkTeacher(courseId, token) == null) {return  null;}
      return  repository.findChaptersByCourseIdOrderByUpdateTimeDesc(courseId);
    }

   private Course checkTeacher(UUID courseId, String token){
        Course course = cRepository.findById(courseId).orElse(null);
        if (course == null){
            return  null;
        }
        UUID teacherId = course.getTeacher().getId();
        if (AuthUtils.invalid(teacherId, token)){
            return  null;
        }
        return  course;
   }

    @Override
    public List<Chapter> getStudentsChapters(UUID courseId, String token){
        Course course = cRepository.findById(courseId).orElse(null);
        if (course == null){
            return  null;
        }
        List<User> students = course.getStudents();
        UUID studentId = AuthUtils.getUser(token).getId();
        long count = students.stream().filter(s -> s.getId().equals(studentId)).count();
        if (count ==0){
            return  null;
        }
        return  repository.findChaptersByCourseIdAndOpenOrderByUpdateTimeDesc(courseId,true);
    }

    @Override
    public  Chapter add(UUID courseId, Chapter chapter, String token){
        Course course = checkTeacher(courseId,token);
        if (course == null){
            return  null;
        }
        chapter.setCourse(course);
        return  repository.save(chapter);
    }

    @Override
    public Chapter update(UUID id, Chapter chapter, String token) {
       Chapter old = repository.findById(id).orElse(null);
       if (old == null){
           return  null;
       }
       UUID teacherId = old.getCourse().getTeacher().getId();
       if (AuthUtils.invalid(teacherId,token)) {
           return null;
       }
       old.setDescription(chapter.getDescription());
       old.setName(chapter.getName());
       old.setOpen(chapter.isOpen());
       old.setUpdateTime(new Date());
       return  repository.save(old);
    }

    @Override
    public Chapter openCloseChapter(UUID id, boolean open, String token) {
        Chapter old = repository.findById(id).orElse(null);
        if (old != null){
            old.setOpen(open);
        }
        return  update(id,old,token);
    }

    @Override
    public Messages remove(UUID id, String token) {
       Chapter chapter = repository.findById(id).orElse(null);
       if (chapter == null){
           return  Messages.WRING_ID;
       }
       UUID teacherId = chapter.getCourse().getTeacher().getId();
       if (AuthUtils.invalid(teacherId,token)){
           return  Messages.No_PERMISSION;
       }
       if (chapter.getQuestions().size() > 0){
           return  Messages.RELATED_DATA;
       }
       repository.delete(chapter);
       return  Messages.SUCCESS;
    }
}
